Profs’ water-cleaning system could save campus thousands of gallons, dollars

Alison Hewitt |
August 04, 2011

Alison Hewitt/UCLA

Professors Yoram Cohen, left, and Panagiotis Christofides, right, and their team of grad students developed the ground-breaking Com2RO system, above, a smart water-cleaning system.

UCLA’s power plant had something that professors Yoram Cohen and Panagiotis Christofides wanted: hopelessly filthy water. And they have invented something that the Cogeneration Plant wanted: a way to clean it up.

Now, a combination ultra-filtration/reverse-osmosis system, devised by the UCLA Water Technology Research (WaTeR) Center, is chugging away in the basement of the Cogen. It’s part of a pilot project that could save UCLA millions of gallons of water as well as hundreds of thousands of dollars. The Cogen uses the water to cool machinery, but evaporation concentrates the minerals and particles from the city's tap water, forcing the Cogen to drain 80,000 gallons daily. While UCLA considers using the WaTeR Center’s system on a permanent basis, the pilot program is giving the research team a chance to perfect its work for other applications.

The system is dubbed Com2RO: a compact, second-generation, reverse-osmosis system, created by the WaTeR Center, where Cohen and Christofides work in addition to being professors in the chemical and biomolecular engineering department at UCLA’s Henry Samueli School of Engineering and Applied Science.

What makes Com2RO unique is both its small size — designed under a grant from the Navy to fit into the watertight hatch doors of their ships — but, more importantly, the way the ultrafiltration (UF) and reverse osmosis (RO) modules of the system “talk” to each other. Most water-cleaning systems — “dumb” systems — fail when confronted with a change in water quality, Cohen said. In contrast, Com2RO is a smart system.

“Basically, this integrates ultra filtration with reverse osmosis in a new design that allows [the two operations] to talk to each other,” Cohen said. “They can handle changing water-quality conditions, and the system figures out what adjustments to make.”

It’s a truly smart system, Christofides said. “You press a button and it works on its own.”

The implications are huge and far-reaching: While water-cleaning systems have traditionally needed to be adjusted or even redesigned to handle different kinds of dirty water, the Com2RO could produce freshwater in poverty-stricken countries without experts to adjust the system if polluted water becomes more mineralized or salty. It could also be used on Navy ships to produce drinkable water from both salt water and gray water.

If the system can reclaim 50 percent of the water it processes — that’s the conservative figure the Cogen is starting with, but Cohen thinks it could go as high as 70 or 80 percent — Com2RO could also help UCLA’s Cogen power plant save around $117,000 and 14.6 million gallons of water annually.

“We’re going to conquer water scarcity,” said Cohen. “Imagine having these systems around the world in places where water is the cause of wars.”

Starting in the basement

Before Com2RO could do any of those things, it needed a large-scale proving ground to complete the final phases of development, Cohen said. Enter the Cogen.

“They needed a good source of water — actually, they needed a bad source of water,” joked Lewis Rosman, the director of energy services at the Cogen plant, which disposes of 80,000 gallons of over-mineralized water every day. It was a perfect match.

“Soon, we’ll be able to treat this water and get an estimated 50-60 percent back,” Rosman said. At current water prices — “which are only going up,” he noted — the savings would cover the cost within two years, instead of the usual four to five years with most green tech, Rosman said. “No other UC [campus] is doing this.”

The plant’s water is used to cool hot oil that lubricates Cogen machinery, Rosman explained. Overheated oil cools by running through pipes past cold-water pipes. Eventually, the water overheats and is sent to the roof, where it air-cools in steaming waterfalls. The falls pick up particles from smoggy L.A. air like a rainstorm cleaning the skyline, and the steam means evaporation. It's a double-whammy of more solids and less water.

“As it evaporates, the solids in the water stay behind and get more concentrated — mostly minerals and chemicals that are naturally in the tap water — and it’s bad for the system,” Rosman said. “It’s like clay.” Hence the 80,000 gallons of blowdown water dumped each day.

In February, Cohen, Christofides and their team of researchers set up Com2RO in the basement of the Cogen, and last week, the machine began continuous operation. The research team — including four UCLA engineering grad students and a postdoc who have been working together on the project for two years — is confirming the quality of the purified water, which is good enough to drink, Cohen noted.

The use of the Cogen as a proving ground for technology invented at UCLA is a model for future projects, said Nurit Katz, the university’s sustainability coordinator. “We’re learning to integrate research and operations.”

Com2RO is currently converting 60,000 gallons of unusable dirty water into 30,000 gallons of clean drinking water every day, Cohen said. It’s not just about proving the system works; it’s also a competition. The Cogen plant will probably request proposals from the WaTeR Center team and two other bidders, Rosman said.

An unexpected windfall

This isn’t the first time that the Cogen will use reverse osmosis to reclaim water. When excavation for the Ronald Reagan UCLA Medical Center hit the water table in 2004, the health system planned to pay to sewer the water until officials realized the neighboring Cogen could use it. By pumping the water to the plant, the hospital was freed from the sewer costs to get rid of 70,000 gallons a day, and, with a little reverse osmosis, the Cogen gets clean water daily.

The difference between the water from under the hospital and the blowdown water the Cogen dumps daily is that the dumped water is much dirtier, Rosman said.

“The hospital water is mostly salty. Our waste water is a different quality of water, with too many solids,” he said. “The existing reverse osmosis couldn’t handle our waste water.”

How Com2RO works

Com2RO can handle the Cogen’s blowdown water because of the combination of ultra filtration and reverse osmosis, Cohen explained. Reverse osmosis is designed primarily for removing dissolved salts — water passes through the reverse osmosis while the dissolved salt ions are repelled — but the RO membranes would choke on larger particles. Ultra filtration steps in ahead of the osmosis to remove micro-organisms and other particles larger than salts, Cohen said.

Com2RO’s smarts are what allows it to shift for different kinds of water. Normally, a similar system would need two large tanks — one to hold the water between the two cleanings, and another to clean the UF filter as often as every half hour, Cohen said.

“A system like that would take a lot of space,” Cohen said. “We eliminate all those intermediary tanks, and the UF determines on its own whether to clean itself.”

Putting the system to work off campus

After wrapping up tests in the Cogen plant, the Com2RO will move to the Naval base at Port Hueneme. “It was designed as a compact system, so it can fit into the 30-by-60-inch water-tight hatch doors. … That also means that at the Cogen, there’s no need for a major reconstruction effort to install it.”

The Institute for Technology Advancement at the UCLA’s engineering school is working with Cohen and Christofides to commercialize the system.

Cohen’s team is also working on a project to desalinate agricultural drainage water in the San Joaquin Valley, where salty runoff has tainted fields so badly they’re unfarmable, he said. “We’ll be going from site to site showing how our remotely operated system can be run via the Internet,” he said.

That means that experts don’t need to be where the system is, and, instead of huge plants, you can have small ones that can be moved around, he said.

“We hope it will make a big splash,” Cohen said, “figuratively speaking.”